[Epidemiology of ulcerative colitis--comparison between Japan and western countries].

Epidemiological data of ulcerative colitis both in Japan and other countries were presented. The prevalence has been increasing in Japan in the past few decades, although it is still lower than that reported from western countries. The incidence in Japan as well as other countries in Asia is increasing. On the other hand, the incidence in western countries has been reported to be decreasing in some reports. There seems to be no significant difference in age of onset between Japan and western countries. Cause of death in patients with ulcerative colitis has changed in Japan after 1980. Death related with colorectal cancer has been increasing in the past 25 years in Japan.